First, there is something dirty with the premise of this idea because it makes terrorism a problem of the entire Muslim collective. Perhaps those individuals who make this argument were in a coma during the 20th century when most of us realized that to treat all the people of any one religion, ideology, or race, as a collective is not only bigoted, but downright dangerous.
Second, heaping an expectation on Muslims - to call out "their" criminals - is absurd when no similar expectation is placed on any other religious, ethnic, or ideological group. Is it appropriate for a white man to tell "the hispanics" to make proclamations against the drug trade? Why should a hispanic who has never even touched drugs speak out against drug lords? His abstention from engaging in the drug trade is condemnation enough. The same goes for Muslims and terrorism. If you want a Muslim to condemn terrorism, realize that he has done so by not engaging in it. Life becomes quite insufferable for Muslims if before speaking about any subject a Muslim is required to first "demonstrate" that he is not "on the side of the enemy." This has had a huge chilling effect on artistic and intellectual production by Muslim youth
Third, in our digital age, it is an act of egregious ignorance for a human being to actually verbalize the words: "Do Muslims condemn terror?" Here is a suggestion from a lowly immigrant: try this thing called "googling." Start with using the search terms "Muslims condemn terror." This was the first hit for me, how about you?
Finally, the reality is that condemnations of terrorism have been pouring in for years. The reasons that so many Americans are still ignorant about them are because they have willfully chosen not to pay attention. Having traveled internationally quite a few times since 2001, I can confidently say that our media has one of the lowest IQs about Islam anywhere in the world. It is - and should be - downright shameful that when I speak to British audiences, I am able to have intelligent discussions about complicated points of Islamic history; meanwhile, now six years since 9/11 and in the US I am still clarifying the simple point that Muslims soundly oppose terrorism